POS0998 DEPRESSION IN SPONDYLOARTHRITIS: THE CHOICE OF MEASUREMENT INSTRUMENT MATTERS
Authors: C. Webers, U. Kiltz, J. Braun, D. Van der Heijde, A. Boonen
Journal: Annals of the Rheumatic Diseases (2022)

Background The prevalence of depression is increased in spondyloarthritis (SpA). Research on this topic in SpA is challenging for several reasons, one of them being the wide variety of different instruments used to assess depressive symptoms. It is unknown whether these instruments are comparable in measuring the construct ‘depression’ and can be considered interchangeable. If these instruments actually differ in what they measure, this should be taken into account when designing and interpreting studies, and in clinical practice when monitoring patients with SpA. Objectives To compare the constructs of several instruments used to assess depressive symptoms in patients with SpA. Methods Data from the international ASAS Health Index Validation Study were used. Included patients had a diagnosis of SpA and fulfilled the ASAS classification criteria for axial/peripheral SpA. Data on demographics and disease characteristics were collected. The following instruments that have been used to assess depressive symptoms in SpA were available: the depression subscale of the Hospital Anxiety and Depression Scale (HADS-D), the Short Form 36 (SF-36) and item 5 of the 5-level EuroQoL 5D (EQ-5Di5). The HADS-D ranges 0-21 (best-worst), with scores ≥8 and ≥11 indicating possible (HADS-possible) and probable depression (HADS-probable), respectively. The SF-36 was summarized using all 36 items in a Mental Component Summary (SF-36MCS, score ≤40 indicating depression), or using only 5 items in the Mental Health subscale (SF-36MH, score ≤56 indicating depression). For the EQ-5Di5, a score of at least “moderately” (level ≥3 on 1-5 scale) or “severely” depressed (level ≥4) indicated depression. Spearman correlations between instrument scores, agreement (kappa) between depressed states, and test characteristics (sensitivity [SE], specificity [SP], positive and negative predictive value [PPV, NPV]) were calculated with HADS-D as external standard, as it was specifically designed to detect depression and considered to have highest content validity. Results In total, 1548 patients were included, of which 1281 (83%) had axial SpA, mean age was 41.6 (SD 13.5) years, 1005 were male (65%), mean symptom duration 14.5 (11.4) years, mean ASDAS 2.6 (1.2) and BASDAI 4.1 (2.5). The prevalence of depression varied around 1 in 3 patients for the lower thresholds of depression (32% for HADS-possible, 45% for SF-36MH, 33% for SF-36MCS and 24% for EQ-5Di5-moderately) and was lower for the more stringent thresholds of HADS-probable (15%) and EQ-5Di5-severely (6%); 192 patients (24% of those who scored positive for depression on ≥1 instrument) scored positive on all instruments (Figure 1). Correlations between instruments were moderate (rho = 0.59-0.66), except between SF-36MH and MCS (rho = 0.85). Agreement between instruments was moderate for lower thresholds for depression (pairwise kappa = 0.47-0.58 for HADS-possible, SF-36MCS, SF-36MH, EQ-5Di5-moderately) and substantial for higher thresholds (pairwise kappa = 0.75 for HADS-probable/EQ-5Di5-severely). Using HADS-D as external standard, EQ-5Di5 was very specific but less sensitive, while SF-36MCS/MH were more sensitive but less specific (Table 1). Table 1. Test characteristics of instruments External standard: HADS-D≥8 (possible ) Definition of ‘depression’ SE SP PPV NPV EQ-5Di5 ≥3 (moderate) 51 89 69 80 EQ-5Di5 ≥4 (severe) 17 99 85 72 SF-36MCS ≤40 68 83 66 85 SF-36MH ≤56 78 71 56 87 External standard: HADS-D≥11 (probable ) Definition of ‘depression’ SE SP PPV NPV EQ-5Di5 ≥3 (moderate) 67 84 41 94 EQ-5Di5 ≥4 (severe) 30 98 68 89 SF-36MCS ≤40 83 75 37 96 SF-36MH ≤56 88 63 29 97 All values are percentages. Conclusion Instruments used to assess depression in SpA are not interchangeable. The choice of instrument should be taken into account when interpreting studies on depression in SpA. SF-36MCS and SF-36MH are sensitive and could be considered for screening while EQ-5Di5 is useful when high specificity is required. In situations where assessment of depression is the primary objective, depression-oriented instruments such as the HADS are recommended. Disclosure of Interests Casper Webers: None declared, Uta Kiltz: None declared, Juergen Braun: None declared, Désirée van der Heijde Consultant of: AbbVie, Bayer, BMS, Cyxone, Eisai, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Lilly, Novartis, Pfizer, UCB Pharma, Employee of: Director of Imaging Rheumatology bv., Annelies Boonen Speakers bureau: Abbvie, Galapagos, Consultant of: Galapagos, Grant/research support from: Abbvie